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Chapter 7. Experimental Validation - Agoraphobia Finally, we analyzed the eye-tracking data for the 10 participants who wore this device. We have not noticed any difference in the types of assessments to the various questions we have asked between users who wore the combined eye- and head-tracking device and those who wore the head-tracking device only. Eye-tracking therefore does not seem to have a significant added value in the determination of a user’s gaze direction. As mentioned at the beginning of this chapter, we also analyzed eye scan velocity and pupil dilation. Indeed, hyperscanning is a symptom found in people suffering from social phobia [Horley et al., 2004] and pupil size is known to increase with anxiety [Marks, 1987]. Our results, however, were not probing. We did not obtain any correlation between eye scan velocity, pupil dilation and the subjective ratings to the questions we asked. However, this is probably due to the fact that we did not deal with a phobic population. We believe that both eye scan velocity and pupil dilation could actually be very good indicators of the presence of increased anxiety depending on the various modes in agoraphobic patients. However, we would need to test our application on such a population to confirm these hypotheses. 7.5 Discussion Simulation related problems. We have encountered several problems in the display of our simulation which have interfered with the features we wanted to evaluate. First, there was no collision detection between characters and with the user. They thus collided with and intersected the user from time to time. For some participants, this considerably reduced their evaluation of character awareness. Here as well, we can mention the uncanny valley effect as there were clearly inconsistencies between character appearance and behavior. Moreover, the frame rate being quite slow due to the complexity in the four-screen display, the scene lagged from time to time, which we believe provoked a decrease in the feeling of immersion. Finally, also due to those quite slow frame rates, we had to display our characters in a lower level of detail. They thus lacked facial animation, which we also believe considerably reduced the feeling of immersion. Combination of gaze and gesture. When we evaluated our application, we allowed for the users to interact with the characters using both gaze and gesture. We believe that we should have evaluated these two forms of interaction separately. Indeed, some participants were distracted by the waving and thus did not pay very much attention to the gazing behaviors. Moreover, when the gesture was not recognized, the characters did not respond. Some participants’ evaluation of awareness and friendliness therefore suffered from this. Computation of Interest Points. We have seen from our results that even though the characters were looking at each other in the random mode, the participants did not perceive their awareness towards each other. We believe this is due to a random choice of interest points to look at instead of a logical one. We thus think that this mode of the application could greatly benefit from the implementation of an interest point detection algorithm as the one we presented in Chapter 4. Validation with a phobic population. Nevertheless, we believe our application to have a high potential in the treatment of agoraphobia with crowds. We believe that it could prove to have very high immersive qualities. Moreover, the application allows the definition of the 116
7.6. Conclusion percentage of the virtual population which should be attentive to its surroundings (should it be other characters, objects or the user). We thus have an application which can be tuned in order to gradually expose patients to increasingly anxiety-provoking crowds. Interaction precision. We believe that we could further enhance our application by allowing more precise interactions using the eye-tracking device. As in the application we presented allowing interaction in the context of social phobia, we could use gaze to define character behavior. For example, we could make them attentive when being looked at in the face and make them nod or wave in return. 7.6 Conclusion In this chapter we have presented a study we have conducted over 30 healthy people in order to evaluate the application we have developed in the context of agoraphobia with crowds. We have tested four different situations, one in which all the characters were interested in the user and gazed at him/her, one where all characters were interested in what the user was looking at and paid attention to that object/character, one in which the characters either looked at the user or at what the user was looking at, and finally, a last situation in which the characters randomly gazed at any other character in the scene, user included. The results we have obtained show that there was a clear identification of the user-centered and the random modes. Participants to the experiment noticed that they were being stared at by all characters in the former and that none of them were looking at them in the latter. We have also been able to outline that there were tendencies in correlations between gaze, immersion and perceived friendliness of characters. From our results, we have also seen that our application could benefit from improvements, which we have discussed in the previous section. Nevertheless, we strongly believe that this form of gaze based interaction can greatly amplify the immersive properties of such applications dedicated to the treatment of phobias. 117
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Simulating Interactions with Virtua
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3.2.4 Scripts . . . . . . . . . . .
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7.3 Experimental Protocol . . . . .
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Résumé La Réalité Virtuelle (RV
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CHAPTER 1 Introduction 1.1 Context
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1.3. Contributions in areas of dail
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1.5. Organization of this Document
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CHAPTER 2 State of the Art 2.1 Virt
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CHAPTER 3 VRET For Social Phobia Mu
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3.5. Gaze Behaviors to Enhance Char
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3.6. Discussion 3.6 Discussion Filt
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CHAPTER 4 Simulating Visual Attenti
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CHAPTER 5 Interaction with Virtual
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Page 141 and 142: Bibliography BIBLIOGRAPHY American
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